零价铁用于砷污染地下水修复的影响因素及效果

Arsenic Contaminated Groundwater Remediation Using Zero Valent Iron:Influencing Factors and Operation Performance

针对地下水无机砷污染,借助批试验和柱试验,利用铁粉(325目)开展了零价铁去除五价砷的室内研究,探讨了初始pH值、无机阴离子、重金属和腐殖酸对除砷能力的影响,考察了动态运行条件下除砷效果及水质指标的变化。批试验结果表明,当pH值=3.7时,反应120 min后对As的去除率达到78.8%,而pH值=6.9时,反应120 min后去除率达到93.9%;溶液初始pH值显著影响零价铁除砷效果,且与酸性相比中性pH值更有利于除砷;硝酸盐、磷酸盐、硫酸盐、铬和铅均显著加快且促进了零价铁除砷,而腐殖酸显著抑制了除砷能力,且其浓度越高则抑制作用越明显。柱试验结果表明,零价铁除砷效果良好且稳定,对As的去除率始终大于95.0%,出水As浓度始终低于9.5μg/L,出水pH值升至7.6~8.1,出水Eh值降至110~145 m V,出水水质满足《生活饮用水卫生标准》(GB 5749—2006)。零价铁法具有潜在的地下水原位修复工程应用潜力。

According to inorganic arsenic contaminated groundwater, iron powder （325 mesh） was used as zero valent iron （ZVI）. Batch tests were conducted to investigate the effects of initial solution pH, inorganic anions, heavy metals and humic acid on arsenic （ V ） removal by the ZVI. Column tests were carded out to explore the operation performance and the changes in water indices under dynamic op- erating conditions. The results of batch tests indicated that after 120 rain, arsenic removal efficiency was 78.8% at the initial pH of 3.7, whereas the corresponding value was 93.9% at the initial pH of 6.9. Initial solution pH had a significant influence on the arsenic removal by the ZVI, and neutral pH was more favorable for arsenic removal. Nitrate, phosphate, sulphate, chromium and lead all accelerated and promoted arsenic removal. Humic acid could seriously inhibit the arsenic removal, and the inhibition effect increased with its concentration. The results of column tests indicated that ZVI could continuously and steadily remove arsenic, with the removal efficiency of more than 95.0% , the effluent arsenic con-centration of less than 9.5 μg/L, the effluent pH of 7.6 to 8.1 and the effluent Eh of 110 to 145 mV. The effluent quality could meet the requirement of the Standards for Drinking Water Quality （ GB 5749 2006）. The ZVI approach has a potential application prospect in in-situ remediation of arsenic contami- nated groundwater.